Objective To investigate the epidemiological characteristics and control measures of dengue fever in Zhongshan City in 2024, so as to provide insights into optimization of dengue fever control strategies in the city. Methods Data pertaining to dengue fever cases in Zhongshan City in 2024 were collected from the Infectious Disease Reporting System of China Disease Prevention and Control Information System, and the epidemiological characteristics of the cases were analyzed using a descriptive statistical method. The density of Aedes albopictus mosquito was monitored across all 23 townships (subdistricts) using Breteau index (BI) and mosquito ovitrap index (MOI) at midmonth each month from March to December 2024. In addition, the climatic characteristics, case reporting patterns, and corresponding control measures were analyzed during different phases of dengue fever epidemics in Zhongshan in 2024. Furthermore, real-time quantitative reverse transcription PCR (RT-qPCR) assay was employed to serotype the dengue virus among local dengue fever cases with unknown sources of infections. The dengue virus envelope (E) gene was sequenced using Sanger sequencing among dengue fever cases without apparent epidemiological links. A phylogenetic tree was constructed using the neighbor-joining method to infer major transmission chains during the dengue fever epi demics. Results A total of 952 dengue fever cases were reported in Zhongshan City in 2024, including 879 local cases, 57 domestically imported cases from other regions, and 16 overseas imported cases, representing the largest outbreak in nearly two decades. The first local dengue fever case was reported on July 5, and the last one was detected on December 19, with all townships and subdistricts affected. Mosquito monitoring data indicated that both MOI and BI rose rapidly from March to May, and then remained at high levels with fluctuations, and began to decline in October. The dengue fever epidemic was categorized into five distinct phases in Zhongshan, including non-epidemic, pre-epidemic, early-epidemic, peak, and receding stages. During the pre-epidemic and early-epidemic phases, key measures included enhancing sensitivity of case detection, implementing isolation and treatment of hospitalized cases, and carrying out standardized vector control measures in affected communities. In the peak phase, the strategy shifted towards targeted mosquito control in key communities and clinical rescue and treatment emphasized on “preventing severe cases and deaths”. Among 481 local cases with unknown sources of infections, RT-qPCR assay revealed that 68.8% (331/481) were infected with dengue virus type I and 31.2% (150/481) with type II among local dengue fever cases in Zhongshan City in 2024. Phylogenetic analysis revealed two major transmission chains: one originating from imported cases within Guangdong Province around Zhongshan City, and another from cases imported from Malaysia. Late detection of local dengue fever cases contributed to widespread community outbreaks. Conclusions The 2024 dengue fever epidemic in Zhongshan City was of considerable scale, which was primarily driven by imported cases from overseas and surrounding regions, leading to local community outbreaks. The epidemic began in early July, increased rapidly during August and September, peaked in October, and subsequently declined, with a trend consistent with the average pattern observed in previous high-incidence years. By implementing differentiated control measures tailored to each phase of the epidemic, the local transmission of dengue fever was successfully contained in Zhongshan City in 2024.

Objective:To analyze the evolutionary characteristics and variation of etiological agent in an acute hemorrhagic conjunctivitis (AHC) outbreak in a city of Guangdong province in May, so as to provide scientific basis for formulating a new round of measures for prevention and control of AHC epidemic.Methods:In this study, 20 conjunctival swabs were collected from AHC patients, and enterovirus, human enterovirus 70 (HEV70) and coxsackievirus A 24 variant (CVA24v) nucleic acids were detected by real-time fluorescence quantitative PCR. In addition, the VP1 and 3Cpro regions of the CVA24v positive samples were sequenced to analyze their evolutionary relationship with the CVA24v strains circulating in China and abroad.Results:All the 20 eye swab samples were EV-positive, and CVA24v-positive, with a positive rate of 100.00%, and all were HEV70-negative.The genomes of CVA24v in VP1 and 3Cpro regions of CVA24v in 5 and 7 samples were successfully sequenced. Based on molecular characterization analysis of VP1 and 3Cpro regions, it was found that the CVA24v isolated in this outbreak had the greatest nucleotide similarity with the CVA24v strains isolated in Thailand in 2014 and French Reunion Islands in 2015. The phylogenetic analysis of 3Cpro and VP1 regions showed that the CVA24v isolated in this outbreak is clustered together with the CVA24v that was prevalent in Thailand in 2014 and the French Reunion Islands in 2015, and have high affinity. Compared with CVA24v isolated in Guangdong in 2010, Thailand in 2014, and French Reunion Islands in 2015, CVA24v isolated in this outbreak was replaced at 4 amino acid sites in 3Cpro region and 1 amino acid site in VP1 region.Conclusions:The cause of this outbreak is enterovirus CVA24v, which has the highest similarity to CVA24v isolated in Thailand in 2014 and in the French Reunion Islands in 2015. There were new amino acid mutations in both 3Cpro and VP1 regions.

This paper studied the diagnosis and embryology of 20 cases lacking one pulmonary artery out of 2040 patients operated for tetralogy of Fallot. History of severe cyanosis syncope and hemoptysis was usually present in the majority of these patients. The important diagnosis characteristic was asymmetry of plumonary vascularity on X-ray film and the decrease of pulmonary cascular markings on the side without plumonary artery. A right ventricular cardiogram can confirm the absence of one pulmonary artery or the blind-end like change.